DESCRIPTION The long-term goal of this research is to identify mechanisms underlying oxidative damage in human diseases associated with inflammation and oxidative stress. Cysteine and cystine residues in proteins can be oxidized to cysteic acid by strong oxidants encountered in the environment. Currently, there are no fully validated biomarkers for assessing oxidative stress or antioxidant interventions in humans. This project will test the hypothesis that protein cysteic acid can be used to measure the severity and/or duration of in vivo oxidative stress. There are two aims: 1) To prepare a monoclonal antibody against cysteic acid that will recognize this epitope/biomarker in plasma proteins and to develop an ELISA assay for quantification of the biomarker, 2) To use the ELISA assay to assess variability in basal plasma levels of the biomarker and its association with coronary artery and renal disease, conditions that are related to inflammation and oxidative stress. Completion of these specific aims will provide a novel biomarker for population-based molecular epidemiologic studies. Such studies will provide information aimed at the prevention and control of human diseases associated with inflammation and oxidative stress that may occur in environmental disease.